Merge pull request #561 from mjtamlyn/import-errors

When importing settings, don't suppress any old error which happens

4 files changed, 24 insertions, 2 deletions

diff --git a/rest_framework/settings.py b/rest_framework/settings.py
index ee24a4ad..5c77c55c 100644
--- a/rest_framework/settings.py
+++ b/rest_framework/settings.py
@@ -115,8 +115,8 @@ def import_from_string(val, setting_name):
         module_path, class_name = '.'.join(parts[:-1]), parts[-1]
         module = importlib.import_module(module_path)
         return getattr(module, class_name)
-    except:
-        msg = "Could not import '%s' for API setting '%s'" % (val, setting_name)
+    except ImportError as e:
+        msg = "Could not import '%s' for API setting '%s'. %s: %s." % (val, setting_name, e.__class__.__name__, e)
         raise ImportError(msg)
 
 
diff --git a/rest_framework/tests/extras/__init__.py b/rest_framework/tests/extras/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/rest_framework/tests/extras/__init__.py
diff --git a/rest_framework/tests/extras/bad_import.py b/rest_framework/tests/extras/bad_import.py
new file mode 100644
index 00000000..68263d94
--- /dev/null
+++ b/rest_framework/tests/extras/bad_import.py
@@ -0,0 +1 @@
+raise ValueError
diff --git a/rest_framework/tests/settings.py b/rest_framework/tests/settings.py
new file mode 100644
index 00000000..0293fdc3
--- /dev/null
+++ b/rest_framework/tests/settings.py
@@ -0,0 +1,21 @@
+"""Tests for the settings module"""
+from django.test import TestCase
+
+from rest_framework.settings import APISettings, DEFAULTS, IMPORT_STRINGS
+
+
+class TestSettings(TestCase):
+    """Tests relating to the api settings"""
+
+    def test_non_import_errors(self):
+        """Make sure other errors aren't suppressed."""
+        settings = APISettings({'DEFAULT_MODEL_SERIALIZER_CLASS': 'rest_framework.tests.extras.bad_import.ModelSerializer'}, DEFAULTS, IMPORT_STRINGS)
+        with self.assertRaises(ValueError):
+            settings.DEFAULT_MODEL_SERIALIZER_CLASS
+
+    def test_import_error_message_maintained(self):
+        """Make sure real import errors are captured and raised sensibly."""
+        settings = APISettings({'DEFAULT_MODEL_SERIALIZER_CLASS': 'rest_framework.tests.extras.not_here.ModelSerializer'}, DEFAULTS, IMPORT_STRINGS)
+        with self.assertRaises(ImportError) as cm:
+            settings.DEFAULT_MODEL_SERIALIZER_CLASS
+        self.assertTrue('ImportError' in str(cm.exception))